1. Field of the Invention
The present invention relates to a thermostat assembly for installation into a thermostat housing in an engine to control coolant flow therethrough and in particular to an improved means for mounting the thermostat in the engine thermostat housing.
2. Description of Related Art
A conventional thermostat for an engine includes a valve member that is biased to a closed position by a spring and has a capsule of expandable material, such as wax, that expands when heated to move the valve member in opposition to the spring to an open position. The thermostat is often carried in a metal carrier that is placed into a thermostat housing in the engine and held in place therein. The carrier may be held in place by a radiator cap or other easily removed structure for replacement of a faulty thermostat.
The present invention provides an improved thermostat assembly in which the carrier is made of a resilient plastic material and has a handle that is easily manipulated to release the carrier from the engine thermostat housing. In the preferred embodiment, the thermostat housing is a circular coolant fitting integrally formed in the timing gear cover or in a separate housing attached to the cylinder head. The fitting is a cylindrical conduit to which a radiator hose can be attached. The conduit has an annular groove on the inner surface thereof and an inwardly tapered portion spaced from the groove.
The thermostat assembly includes a flow control valve operable in response to the temperature of the coolant to open and close to permit or prohibit flow of a coolant through the valve. The carrier is preferably made of a thermal plastic resin in a single piece molding and carries the valve. The carrier has an annular body portion closely fitting to the inside of the thermostat housing conduit. The body portion includes means to mount the valve therein. The carrier further has a pair of opposite side posts extending axially from the body portion. The posts have outwardly projecting snap tabs that seat within the groove in the housing to hold the carrier therein.
The carrier further includes a handle portion with legs that extend, first inwardly from the upper ends of the side posts and then upwardly to upper distal ends. A cross member connects the upper distal ends of the handle legs. The legs of the handle and side posts are resilient to enable the legs to be pushed radially inward toward one another. This moves the snap tabs radially inward to withdraw them from the grooves in the conduit to enable the carrier and the valve to be removed from the engine thermostat housing. Alternatively, the handle legs can extend both upward and outward to the upper distal ends.
The inner surface of the engine thermostat housing has an inward tapered portion. The carrier body portion engages and seals against the taper portion of the conduit when the snap tabs are seated in the groove. This eliminates the need for a separate O-ring seal between the carrier and the housing. When the valve is closed, fluid pressure acts on the carrier upstream of the valve to push the carrier outward, against the tapered surface of the conduit. The fluid pressure thus helps to create the seal between the carrier and the conduit.